Impeccable (nearly).
The difficulty plus the mind bogglingly amazing code of the bullet hell projectiles is so intense that I just can't believe I get to enjoy something like this on my GBC. This is the best shmup I have played on the system despite its small amount of content. I think its difficulty and arcade nature together with its addictive polished game play means that it can be replayed again and again and beats out any GB or GBC shmup that comes before it (including its predecessor Dangan GB).

I have been playing for a particularly long time now and the only thing I have been struggling with is to reconcile the hitbox size with the size /design of the ship. In heated moments where I need to get through a tight squeeze, the ships sprite simply doesn't give accurate enough information that tells me just how close I can get to a projectile in order to get by some times. More specifically, because the ship is rendered over the bullets, the bullets can be obfuscated enough that I sometimes feel I am just guessing my path through the bullets and hoping for the best.

It would also be great to be able to reset a run when doing high score runs from the beginning rather than have to kill myself until Game Over or resetting the GB.

Given this is a bullet hell, I think you may want to address the ships size and/or make the cockpit pixel more prominent or clearly defined graphically so players can more clearly navigate tight squeezes and see the bullets a little more clearly during near misses. In fact, I ended up making a hacked ROM of my own with an edit to the ship size and made the cockpit pixel more prominent, contact me if you want to check it out. I'm still giving this a 5 star review as its an incredible achievement otherwise. Well done to the dev team!